THE CAUSES OF DEATH 119 



childhood. Out of a thousand infants of each sex exposed 

 to risk, only 7 males and 5 females die from breakdown 

 of this group of organs during the first year of life. 

 The trough of the curve associated with the mortality of 

 childhood and youth is very much less pointed than in 

 the case of "all causes.' It is a smoothly rounded, 

 rather than a sharply pointed depression. It is also 

 noteworthy that between approximately the ages of 5 

 and 35 the specific force of mortality from diseases of the 

 circulatory system and related organs is higher for 

 females than it is for males. This condition of affairs is 

 probably connected with the graver physiological changes 

 and readjustments called forth by puberty in the female 

 than accompany the same vital crisis in the male. From 

 early adult life, say age 25-30 on, the specific death rate 

 from diseases of the circulatory system and related organs 

 increases at an almost absolutely constant rate until age 

 85 is reached. After that, the rate of increase slows 

 down somewhat. Of those reaching the ages 95-100, be- 

 tween 70 and 80 out of each thousand living die from 

 breakdown of this group of organs. 



The specific mortality curve for deaths from break- 

 down of the respiratory system, as shown in Figure 29, 

 presents a number of points of peculiar interest. In 

 the first place we note that this organ system is much 

 more liable to breakdown than is the circulatory system 

 during all the earlier years of life up to about age 60-65. 

 The decline in the curve from the high point of infancy to 

 the low point of the period about puberty is more sharp 

 and sudden than that of the circulatory system curve. 

 Again, however, just as in the former case, we note that the 

 specific force of mortality from breakdown of this organ 

 system impinges more heavily upon females than upon 



